1. Field of the Invention
The present invention relates to a lock assembly, and more particularly, to a lock assembly having a hook suited for sliding doors.
2. Prior Art
The use of sliding doors is well known in the art. However, the lock used on such sliding doors have tended to be rather fragile compared to the type of lock found in most hinged doors. One reason for this fact is that in contrast to a hinged door, the frame of a sliding door is small and it is thus difficult to employ cylinder locks. The most common type of lock which has been used in sliding doors is a plate-key type twist lock system which is unsophisticated and can be easily unlocked by the insertion of any small key-like implement.
In recent times, aluminum sash has become widely used in sliding doors which has resulted in allowing the use of the cylinder-type locks with a hook on such doors. There are two forms that are commonly used. In the case of the first one, the inner and outer fasteners are attached, whereas bifacial fastenings are used with the second.
In the first, since the outer fastening and inner fastening are built with completely incompatible systems, they are in no way related to one another. Accordingly, this means that if the door is locked from the inside, it cannot be opened from the outside and if locked from the outside, it cannot be unlocked from the inside. In terms of security, this method is thought to be the most certain, but it is inconvenient. The above-mentioned plate-key type of twist lock is a good example of this style. The truth is that a really secure product is not yet on the market.
The second is locked and unlocked from the outside by means of a cylinder lock and from the inside by a thumb knob, thus the locking and unlocking operation from both the inside and the outside is the same. Since this is identical to the locking and unlocking method used with hinged doors, this system is considered superior in terms of its convenience and can save substantial time. However, such a system has a significant shortcoming in that since the dimensions of a door frame of a sliding door are restricted, the number of cylinder pins must be limited for the sake of greater convenience. This means that the locking device is substantially simple; thus it is easy to pick so as to gain entry.